Specified cast is not valid in EmployeeUtilityClass - asp.net

Question

i have a table empinf
fields
Empid int
EmpName Nvarchar
Salary Numeric
i have a EmployeeUtility class which contains a Method Getdetails
public EmployeeDetails Getdetails(int employeeId)
{
SqlConnection con = new SqlConnection(connectionString);
SqlCommand cmd = new SqlCommand("SelectEmployee", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("#Id",SqlDbType.Int,4));
cmd.Parameters["#Id"].Value=employeeId;
try
{
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
if (!reader.HasRows) return null;
reader.Read();
EmployeeDetails emp = new EmployeeDetails((int)reader["EmpId"], (string)reader["EmpName"], (int)reader["Salary"]);
reader.Close();
return emp;
}
catch (SqlException e)
{
throw new ApplicationException("Data error.");
}
finally
{
con.Close();
}
}
EmployeeDetails emp=new EmployeeDetails((int)reader["EmpId"],(string)reader["EmpName"],(int)reader["Salary"]);
it shows an error in this line indicating Specified cast is not valid. please need assistance in it.
my employeeDetails class is as follows:
public class EmployeeDetails
{
private int employeeID;
public int EmployeeID
{
get { return employeeID; }
set { employeeID = value; }
}
private string employeeName;
public string EmployeeName
{
get { return employeeName; }
set { employeeName = value; }
}
private int salary;
public int Salary
{
get { return salary; }
set { salary = value; }
}
public EmployeeDetails(int employeeId, string employeeName, int salary)
{
EmployeeID = employeeID;
EmployeeName = employeeName;
Salary = salary;
}
public EmployeeDetails()
{
// TODO: Complete member initialization
}
}

Answer 1

I'm assuming that this error is a runtime exception, and not a compiler error?
The problem is not with your EmployeeDetails class - but on one of these
(int)reader["EmpId"], (string)reader["EmpName"], (int)reader["Salary"]
One or more of the values being populated into the data reader cannot be converted into int or string, either because of a bad type or because it's null.
Since EmpId is likely to be an Identity column, and therefore not null, my money is on either the EmpName column being null or the Salary column actually containing a float, or being null. In the second case, you could use an int?, unless it's just simply dodgy data, in which case make sure the column is not nullable.
You can use the Convert class for converting column values to .net types - because they will actually be Sql types. That said, those types - SqlInt32, for example - does support casting directly to int, for example, but it will also throw an exception if the underlying value is null. That said, so will Convert; so I suppose either will actually do.

Answer 2

This is mostly a guess, but it could be this:
(int)reader["Salary"]
Numeric is a decimal data type, not an integer. But you're trying to directly cast it to an integer. If the Salary value in the database is a decimal, try changing the Salary value on the object to a decimal as well.
Note that you can easily debug this and narrow down the problem in the future by simply removing one field at a time and re-running the test. When you remove a field and it works, re-add the field and it again doesn't work, you've found the culprit.
Note also that your exception handling is woefully poor form:
catch (SqlException e)
{
throw new ApplicationException("Data error.");
}
Not only do you completely ignore the actual exception, but you replace it with another that's entirely devoid of context. You should at least log the exception that occurs.

Answer 3

Try this:
EmployeeDetails emp=new EmployeeDetails(Convert.ToInt32(reader["EmpId"]),Convert.ToString(reader["EmpName"]),Convert.ToInt32(reader["Salary"]));
//this assumes that you don't have NULL values in any of those columns, because if you do, it will fail. It would be more safe to check for DBNull.Value before trying to Cast these values.